Liquid fuel burning apparatus

ABSTRACT

A liquid-fuel burner accessory unit including a liquid ring pump which is positioned in an airtight chamber and delivers compressed air and fuel to this chamber that forms an air-fuel separation chamber. The liquid ring pump includes a stationary valve body defining the intake and outlet with a rotary casing driven by a motor located beneath the chamber, the motor shaft extending up and being connected to the casing. A fuel metering arrangement for delivering a metered fuel output includes pistons and cylinders associated with check valves and driven by a cam on the shaft to provide differential pumping action.

United States Patent [72] Inventor Frank W. Bailey 663 Black Oak Ridge Road, Wayne, NJ. 07470 [21] Appl. No. 810,430 [22] Filed Jan. 21, 1969 [45] Patented June 8, 1971 Division of Ser. No. 526,972, Feb. 10, 1966, abandoned [54] LIQUID FUEL BURNING APPARATUS 2 Claims, 7 Drawing Figs.

[52] U.S.Cl 417/69, 417/215, 417/253, 417/416 [51] Int. Cl ..F04c 19/00, F041) 25/00, F04b 35/04 [50] Field ofSearch ..137/101.25, 101.27, 209, 392; 103/4, 6, 7, 37; 230/79, 45

[56] References Cited UNITED STATES PATENTS 1,224,589 5/1917 Zuber 103/37 Primary ExaminerWilliam L. Freeh Atlorney-Bryan, Parmelee, Johnson & Bollinger ABSTRACT: A liquid-fuel burner accessory unit including a liquid ring pump which is positioned in an airtight chamber and delivers compressed air and fuel to this chamber that forms an air-fuel separation chamber. The liquid ring pump includes a stationary valve body defining the intake and outlet with a rotary casing driven by a motor located beneath the chamber, the motor shaft extending up and being connected to the casing. A fuel metering arrangement for delivering a metered fuel output includes pistons and cylinders associated with check valves and driven by a cam on the shaft to provide differential pumping action.

METEREDFUEL S U PPLY PATENTEUJUM 81% 3583830 I SHEET 2 UP 3 COMPRESSED AIR 1 SUCTION UPPLY 68 METERED FUEL s u PPLY FIG.2

INVENTOR FRANK w. BAHEY EYS Ad Ow ATENTED JUN 8 1971 SIKLET 3 BF 3 Y E L I A B m. w MK N A R F FUEL DIFFERENTIAL RETURN LIQUID FUEL BURNING APPARATUS This application is a division of parent application Scr. No. 526,972 filed Feb. 10, l966,now abandoned.

This invention relates to a liquid-fuel burning process and apparatus for carrying out the process.

In the burning ofliquid fuel such as kerosene, domestic fuel oil, and similar types of liquid fuel, the prior state of the art has made necessary the use of processes and apparatus which are entirely different from those which are used when burning a gas fuel, such as natural gas, manufactured gas, methane, ethane, propane, butane, or the like. Thus, gas burning devices as a class, e.g. domestic gas stoves, domestic gas furnaces and gas room heaters, gas water heaters, and the like, are quite different in structure and operation from liquid-fuel burning devices as a class, e.g. kerosene stoves and kerosene room heaters, domestic oil burners and oil-fired water heaters, and the like. The gas burning devices have been more compact and less expensive than liquid-fuel devices and gas burning devices have produced a cleaner flame, with less soot and smog resulting.

It is an object of the present invention to provide a liquidfuel burning process and apparatus which enable the use of burner units similar to those customarily utilized in gas burning devices.

A further object of the present invention is to provide liquid-fuel burning process and apparatus which produce a clean flame and operate efficiently while being compact.

In accordance with one aspect of the liquid-fuels burning process which is illustrated as embodying the present invention, fuel-free air is preheated to a temperature above that at which a substantial quantity of the liquid fuel vaporizes. The resulting heated air is turbulently and violently mixed with a quantity of the liquid fuel to break up the fuel mechanically and thermally into finely divided fuel particles which are thoroughly mixed with the heated air. A portion of these finely divided fuel particles may be in the vapor state and the remaining portion in the form of very finely divided droplets. In order to stabilize this mixture, the heated air is abruptly chilled by thoroughly mixing with a cool quenching medium and then the resulting stabilized mixture is ready to be burned.

Among the many advantages of the present invention are those resulting from the fact that the process and apparatus converts the liquid fuel into a finely divided mixture with a combustion supporting gas, and the resulting mixture is stable. That is, the tendency for the finely divided fuel particles to agglomerate into larger droplets is largely avoided. As a consequence, this mixture of finely divided fuel and combustion supporting gas can readily be burned in a conventional gas burner device. It can also readily be burned in an internal combustion engine and provides advantages in enabling less volatile fuels such as kerosene and diesel oil to be burned in a conventional gasoline engine of the carburetor type, i.e. without the use of fuel injectors and fuel spray nozzles.

Another advantage of the illustrative embodiments of the present invention are those resulting from the fact that they include a combination unitary fuel pump, fuel metering apparatus, compressed air pump and large flow low-pressure air fan. This combination unit is adapted to serve as an accessory unit for a large range of liquid-fuel burning devices. Moreover, the fuel metering apparatus enables precise metering of small fractions of a gallon of fuel oil per hour by differential pumping action which advantageously achieves this precise measurement without the use of small orifices or small pistons. For example, this fuel metering apparatus will readily operate throughout the range from 2 gallons per hour down to 0.10 of a gallon per hour and can be adjusted to meter any desired delivery rate within this range.

In this specification and in the accompanying drawings are described and shown liquid-fuel burning process and apparatus embodying the invention, and various modifications of the embodiments of the invention are illustrated, and it is to be understood that this disclosure is not intended to be exhaustive nor limiting of the invention, but is set forth for purposes of illustration in order that others skilled in the art may fully understand process and apparatus of the invention and the manner of their application in practical use.

The various objects, aspects, and advantages of the present invention will be in part pointed out and in part will be apparent from the following description of illustrative embodiments of this invention, when considered in conjunction with the accompanying drawings, in which:

FIG. I shows a liquid-fuel burning process and apparatus embodying the present invention utilizing a burner unit similar to a gas burning device;

FIG. 2 is an axial sectional view ofa compact accessory unit which serves the combined functions of fuel pump, compressed air pump, adjustable liquid fuel meter and large flow low pressure air fan;

FIG. 2A is a perspective view ofa valve body hub portion of the apparatus of FIG. 2;

FIG. 3 is a cross section of FIG. 2 taken along the line 3-3 looking downwardly;

FIG. 4 illustrates the differential pump adjustable fuel metering apparatus;

FIG. 5 is a cross-sectional view of air fan, being a section taken along the line 5-5 of FIG. 2 looking downwardly; and

FIG. 6 is an exploded perspective view illustrating an eccentric drive mechanism included in the pump apparatus apparatus of FIG. 2

As shown in FIG. I the liquid-fuel burning process illustrative of the present invention includes the step of preheating fuel-free air to a temperature above that at which a substantial quantity of the liquid fuel 10 vaporizes. This liquid fuel 10 is shown as No. 2 fuel oil being supplied from a suitable oil reservoir 12. There are two alternative ways in which the air is preheated in this system of FIG. 1. During the initial brief period of operation when the process is first being started up the air is preheated by an electrical heating element 14 which is energized from a suitable electrical source 16 through a relay switch 18 which is normally closed. After the system has been in operation for a brief period to accomplish warm-up, then a solenoid valve 20 is opened so that the air is preheated by means of a coil 22 which is in heat exchange relationship with the combustion flames 24. As soon as the heating coil 22 has fully warmed up, the electrical heater 14 is deenergized by energizing a solenoid 25 so as to open the switch 18.

The resulting heated air is turbulently and violently mixed with a quantity of the liquid fuel in a first chamber 26 which serves the purpose of mechanically and thermally breaking up the liquid fuel into finely divided particles. The elevated temperature of the heated air vaporizes a substantial portion of the fuel and the remaining portion is violently sheared and churned to break the fuel up into very finely divided droplets. This first chamber 26 has an elongated cylindrical configuration terminating in an output nozzle 27, and the heated air is introduced into an input region 28 at the opposite end of chamber 26 from the nozzle 27.

This heated air passes through a constriction 29 which is aimed at an angle within the chamber 26 to produce a violent helical swirling movement of the heated air within the chamber 26. The cool liquid fuel is introduced through fuel inlet means 30 in the form of a tube which is angled forwardly into the chamber 26, and the violently swirling air shears and breaks up this fuel. The intimate and violent mixing of the heated air and cool liquid fuel within this fuel break up chamber 26 promotes a very effective and rapid heating up of the fuel particles. There is a high heat flux from the swirling air into the fuel particles by conduction and convection, that is, by relative motion and scrubbing action between high speed masses of gas. This high heat flux promotes rapid vaporization and mechanical shearing and break up of the fuel into very finely divided droplets. The swirling mixture of heated air and finely divided fuel (vapor and very tiny droplets) progress along within the chamber 26 toward the nozzle 27 and issues therefrom as a jet 32 which is directed into the bell mouth 34 ofa burner unit 36 which is similar to a gas-burning device.

Within the fuel break up chamber 26, the ratio of fuel to air is usually above a stoichiometric ratio thus avoiding any possibility for combustion to occur within this chamber 26.

As the hot jet 32 enters the funnel shaped entrance 34 it draws in a large flow 38 of atmospheric air which serves as a secondary air flow to support combustion and is a cool quenching medium to stabilize the finely divided fuel particles. it is my theory of explanation as to why this sudden cooling quenching stabilizes the finely divided particles that it markedly slows down the thermal agitation of the vapor and finely divided particles. This reduced thermal agitation reduces the number of collisions between the tiny particles of fuel and fuel vapor molecules and so it retards the agglomeration of the fuel into larger droplets. Regardless of whether this is a correct theory, the flow of cool quenching medium 38 does stabilize the finely divided fuel particles suspension within the barrel passage 39 of the burner 36. Hence, the tiny fuel particles remain suspended within the barrel passage 39 and become thoroughly mixed with the flow 38 of combustion supporting gas.

This combustible mixture is ignited by ignition means 40 shown as an electric spark plug. Any suitable ignition means such as 1 hot wire, glow plug, or the like, may be used. After the warm-up period the combustion process will continue selfsustaining so long as the jet 32 continues, and so the ignition means 40 may then be turned off ifdesired by conventional ignition control mechanism.

The flames 24 pass up within a shroud 42 and are in heat exchange relationship with the air preheater coil 22. These are clearly burning blue flames which are very similar in characteristics to the flames produced by burning gaseous fuel. The burner unit 36 may be formed of cast iron, and an adjustable baffle (not shown) is provided at the entrance to the bell mouth 34 so as to adjust the quantity of the air flow 38 relative to the jet 32, as is provided in a conventional gas burner unit.

The system of FIG. 1 includes a compact accessory unit A which provides the combined function of delivering compressed air, pumping fuel, metering fuel and delivering a large flow of low pressure air. This compact apparatus is shown in FIG. 2 and will be explained further below. It includes a liquidring pump P which produces suction in an intake line 44 and is capable ofdrawing either air or liquid fuel or a mixture of both into the intake line 44.

In the system of FIG. 1 the liquid fuel 10, for example such as kerosene, Nos. 1 and 2 fuel oil, and the like, is drawn up from the storage tank 12 through a fuel supply line 45 and through a strainer 46 and a line 47 to a three-way solenoid valve 48 which is connected by a suction line 49 to the pump intake 44. Air is drawn into the system through an air intake filter 50 which is connected by a line 51 to the valve 48. There is an adjustable restriction 52 in an air bleed connection 53 which extends to the suction line 49 to bypass the valve 48, so that a sufficient quantity of air is always being supplied to be preheated as discussed above. The solenoid value 48 is operated by a float 56 (FlG. 2) which operates a mercury control switch 57 in response to the liquid level 58 within an airfuel separation chamber 59 which is included in the compact unit A.

From the liquid-ring pump P the fuel is supplied in metered quantity through a fuel supply line 60 to the fuel feed tube 30. In order to keep the fuel cool before it enters the chamber 26, the tube 30 is surrounded by cooling fins 62.

Fuel-free compressed air is delivered from pump P through an air supply line 64 and a shut off valve 66 to a tee connec tion 67. From this connection 67 one branch passes through an adjustable restriction 68 and through a conduit 69 into the region 28. The conduit 69 is heated by the heater element 14. The other branch 70 extends through the solenoid valve to the heating coil 22 and returns through a line 71 to the region 28. The valve 20 is controlled by a thermostat 72 which senses the presence of the flames and then opens this valve 20, thus bypassing the restriction 68 and conduit 69. An oil bleed bypass connection 72 extends through a restriction 73 back to the suction line 49.

Instead of igniting the combustible mixture in the venturi portion 34 of the burner unit 36, the ignition means 40 may be located in the passage 39 or in the flame region 24, whatever location may be desired for different applications.

As shown in H0. 2, the burner accessory unit A includes the liquid-ring pump P. The pump drive means which may be any suitable rotary drive means for example such as an electric motor has its shaft 82 directly coupled by key 83 to a rotating hub section 84 which is attached to one radial wall 85 ofa rotatable pump casing 86. The wall of the rotary casing 86 has a cup shape and is clinched onto a hub sleeve member 88 which serves as a sleeve valve. This hub member 88 rotates about a stationary shaft 90 forming a valve body having a suction intake passage. 44 and a discharge passage 92 extending longitudinally therein, the latter communicating through a lateral passage 93 with the fuel-air separating chamber 59.

The fuel-air separating chamber 59 is a sealed chamber being an integral part of the accessory unit A. This chamber 59 is defined by a cylindrical housing 94 and a cover 95 which is removably secured and sealed to the housing 94. The valve body 90 is rigidly held by the cover 95, and the whole housing 94 is mounted on a base frame 96. The compressed air supply line 64 is connected to the chamber 59, and the suction line 49 is connected to the suction passage 44 within the valve member 90.

A plurality of impeller blades 98 extend radially within the rotatable casing 98. These blades 98 define sector shaped pockets 100 which are uniformly positioned about the hub sleeve member 88, and valve ports 108 extend out through this sleeve member 88 into the pockets 100. These ports 108 provide communication between the pockets 100 and a pair of recesses 102 and 104 (FIG. 2A) in opposite sides of the valve body 90 which serve as the intake and discharge chambers communicating with the passages 44 and 92.

During operation of the pump P, the casing 86 and impeller blades 98 rotate, and the liquid fuel 10 within the pockets 100 is centrifuged out to form a stable liquid ring having an interface with the air 11] which is being pumped and compressed.

in order to produce a pumping action, an eccentrically positioned circular rotor 114 displaces the liquid 10 into and out of the pockets 100. This rotor 114 is mounted on a ball bearing assembly 116 FIGS. 2 and 2A) which is held by a stub shaft 118 projecting from the end of the valve body 90. In this embodiment the rotor 114 is freewheeling. As shown in FIG. 2 the perimeter of this rotor 114 slopes inwardly toward the pockets 100, and there are numerous small square-ended blades 118 projecting out from the perimeter of the rotor.

These rotor blades 118 perform three functions. (1) They prevent the liquid fuel from eddying around the edges of the rotor blades 98, thus providing additional stability in the liquid ring and increasing the total pump displacement efficiency and output pressure. (2) They prevent a compressional shock wave from transmitting itself backward through the revolving liquid ring toward the suction side, thus further stabilizing the liquid ring. (3) They impart torque hydraulically for rotating the free rotor 114 so that it turns at substantially the same speed as the casing 86, thus avoiding turbulence losses in the liquid.

Although these rotor blades 118 do improve the performance substantially as explained, this pump will operate satisfactorily without them, i.e., with a purely disclike rotor, for applications in which the added simplicity of the pump is desirable and its lower output pressure and efficiency are acceptable.

A circular baffle plate 120 is clinched onto the opposite end ofthe sleeve 88 from the casing 86, and this baffle extends out over the impellers 98 near to the face of the rotor 114 so as to separate the liquid in the interior of the pockets 100 from the rotor 1 14.

The effective inward and outward motion of the liquid-air interface 110 produces a strong suction in the intake recess 102 and intake passage 44 and produces a strong compression in the discharge recess 104 and discharge passage 92. This pumps compressed air through the lateral passage 93 into the chamber 59 and also some liquid fuel is pumped with the air into this chamber to create a fuel level 58. When this level rises, the float 56 and switch 57 operate the valve 48 (FIG. 1) to shut off the flow of fuel up through the line 47. Consequently, only air is then drawn through the valve 48. There is always a small recirculation of oil through the bypass connection 73 and restriction 74 so as to maintain the liquid ring 110 in the rotating casing 86. Conversely, when the liquid level 58 falls, the valve 48 is again opened to admit fuel from the supply line 47 into the suction intake line 49.

In the modified embodiment of the liquid ring pump P shown in FIG. 6 the rotor 114 is positively driven by a drive coupling 122. This drive coupling includes a first disc 124 which is secured to the rotating wall 85 and has a diametrically extending groove 125 therein. An intermediate coupling disc 126 of Nylon has radial rigs 127 and 128 on opposite surfaces extending at right angles to each other. The pair of ribs 127 engage in the groove 125, and the ribs 128 engage in another groove 129 in a disc 130 which is secured to the rotor 114. Thus, the rotor 114 is positively driven at the same revolutions per minute as the pump casing 86, and this coupling 122 accommodates the eccentricity ofthe rotor 114.

The liquid fuel provides lubrication within the pump P for the rotation of the ported sleeve 88 around the valve body and for the rotor bearing 116 and also for the positive drive coupling 122, in the embodiment including this coupling.

In order to provide positive displacement fuel metering of the fuel being fed to the conduit 30, a differential pump metering mechanism M (FIGS. 2, 3 and 4) is enclosed within the air fuel separation chamber 59. There are many advantages in the use of this metering apparatus M. It avoids mass flow variations of the fuel due to variations in the viscosity of the liquid and thus continuously maintains the desired firing rate and prevents sooty inefficient combustion throughout the range of operation.

This differential pump metering mechanism includes a plurality of cylinders and pistons which cooperate to provide a controllable and positively displaced metered volume of liquid at a low flow rate per hour. This low flow rate is advantageously provided even though the displaced volume of each of the pistons in their respective individual cylinders is many many times larger than the metered output.

The fuel is drawn from the chamber 59 through an intake port 140 and trough a spring-biased ball-check valve 142 into an intake passage 143 communicating with the interior of a cylinder 144 withinwhich is reciprocated a plunger-type piston 146. This piston 146 is driven by a nutatir tg eccentric ring sleeve 148 within which revolves an eccentric 150 secured to the motor shaft 82 by a pin 151 (FIG. 2). The ballcheck valve 142 is held in a socket 152 supported by an arm 153 which is secured to a ring 154 surrounding the mounting 156 of the central bearing 158 for the motor, pump and fan shaft 82. This mounting 156 is fastened to the lower end ofthe housing 94 and is sealed thereto by a seal 160.

In order to accommodate the nutating motion of the eccentric ring 148 as the eccentric 150 revolves, swivel mounting means 162 are provided for the cylinder 144. The inlet passage 143 is located in a bushing 162 which is adapted to swivel within the socket 152.

For purposes of adjusting the metered output, as will be explained further below, the arm 153 can be adjusted in angular position as indicated in FIG. 3 by turning the ring 154 about the mounting 156. In FIG. 3 the full-line drawing shows the cylinder 144 at one limit of its range of adjustment and the dashed-line drawing shows the cylinder and arm at an intermediate position 144', 153' within the range of adjustment. A gear sector 164 is engaged by a pinion gear 165 on a vertical shaft 166 which can be turned by an index knob 168 connected through gears 169 and 170 to turn the shaft 166 for swinging the arm 153 and cylinder 144 about the mounting 156.

As shown in FIGS. 3 and 4, the fuel is pumped out of the passage 143 through a tube 171 and through a ball-check valve 172 connected to a flexible tube 174 leading to a tee joint 175 connected through a spring-biased ball-check valve 176 to a metered fuel output port 178. As shown in FIG. 2 this port 178 communicates through a conduit 179 to the fuel supply line 60.

From the tee joint 175 a tube 180 provides a branch flow path extending to a second cylinder and piston unit including a passage 143a in a swivel bushing 162a supported by a socket 1520 on an arm 1530. This arm 153a is rigidly secured to the mounting 156 by means of a key 182 (FIG. 2) engaging the ring 154a. Thus, the operating position of the cylinder 144a is secured. From within the passage 143a the fuel can flow past a spring-biased ball-check valve 182 and pass through a return port 183 into the chamber 59. It is noted that the ball 182 conveniently seats against the lower end of the swivel bushing 162a within the socket 152a.

In operation, the piston 146a is driven by the same eccentric 150 which drives the piston 146, but their respective strokes are displaced in time by an amount determined by the adjusted angular position of the mounting arm 153 relative to the fixed arm 153a. When the piston 146 is diametrically opposite to the piston 146a, their strokes are displaced 180 in time, i.e. they are moving exactly out of phase, and consequently there is no fuel being fed through the output line 60; all of the fuel is returned through the valve 182 and port 183 into the chamber 59. This is the fuel differential return flow, and as will be understood it equals the total flow when there is no metered output.

As shown in FIG. 3, as the operating position of the cylinder 144 is adjusted in the direction of the arrow 184, by turning the knob 168 (FIG. 2), the phase differential between the strokes of the two pistons 146 and 146a is progressively reduced from 180 toward zero. This progressively reduces the flow rate of the differential return and correspondly increases the metered output.

In order to assure the delivery of bypass fuel through the connection 73 and restriction 74 to the suction line 49, it is advantageous to connect the return port 183 to the line 73. This assures that there is always some liquid being fed into the liquid-ring pump P so as to maintain the desired depth and geometry of the liquid ring 110.

Among the advantages of this adjustable differential pump fuel metering apparatus are that the cylinder and pistons may be relatively large even though the metered output flow is very small. The apparatus is adjustable over an abnormally wide range down to zero. The piston and cylinders are of low cost construction and all of the moving parts are in continuous contact, thus eliminating chattering or other noise and wear factors. It will be noted that the flow rate can be adjusted at any time regardless of whether the burner is in operation or not.

By virtue of the fact that the cylinders 144 and 144a are supported by bushings defining the inlet and outlet lines, this enables the driving eccentric 150 to exert maximum mechanical advantage on the rings 148 and 148a with respect to the swivel joints. Therefore, these swivel joints can be sealed very tightly against leakage without imposing a difficult starting or running torque on the motor 80.

In addition it is noted that because it is a differential volume metering system, the series of check valves are more reliable, particularly for high speed operation. There is a relatively high throughout rate through all of these check valves, except 176, and this high throughput rate reduces any tendency for cavitation to occur and also reduces the susceptibility for fouling due to dirt particles or lint which might be entrained in the fuel oilor similar liquid fuel. Also, the large throughput rate enables the use ofstandard size check valves because the volumetric displacement of the movable ball check is small relative to the large instantaneous fluid displacement.

The accessory unit A also includes a fan (FIGS. 2 and 5) attached to the end of the shaft 82 for delivering a relatively large flow of combustion supporting air at low pressure. The air 192 is drawn in through ports 194 in the motor housing 196 which is secured to the lower end of the pump housing 94. This air flow passes down through suitable openings in the stator and rotor laminations 197 and 198 to cool them and the motor windings 199. The fan blades 200 are adapted to receive an axial flow 201 and to impell the air out into a scroll 202.

A movable cylindrical damper 204 controls the output flow rate 205 into a duct 206 (FIG. 1) by adjusting the relative amount of air passing through an output opening 207 and through a bypass opening 208. The arcuate length of the damper 204 is sufficient to block off a proportion of one opening 207 or 208 which is equal to the remaining unblocked area of the other opening. Thus, the maximum cooling flow rate 192 is maintained through the motor regardless of output flow rate 205.

The duct 206 is connected to an apertured manifold 210 which supplies a forced draft into the shroud 42 around the flames 24. A valve 212 can also be used to adjust this flow rate, and a branch duct 214 directs air over the cooling fins 60.

From the foregoing it will be understood that the various embodiments of the liquid-fuel burning process and apparatus of the present invention as described above are well suited to provide the advantages set forth. It will be appreciated from the foregoing that many possible embodiments may be made of the various features of this invention and the apparatus herein described may be varied in various parts, all without departing from the scope of the invention, and that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense, and that, in certain instances, some of the features of the invention may be used without a corresponding use of other features, all without departing from the scope of the invention.

WhatI claim is:

1. A liquid-fuel burner accessory unit comprising a housing defining an airtight chamber, a liquid-ring pump positioned within said chamber, said pump having a suction intake for fuel and air and having an outlet feeding into said chamber for delivering compressed air and fuel into said chamber, said chamber forming an air-fuel separation chamber, fuel level control means for controlling the fuel level in said chamber, an output from said chamber for delivering compressed air, fuel metering means communicating with said chamber for delivering a metered fuel output therefrom, an electric motor connected to said liquid-ring pump driving said pump, said pump having a rotating casing driven by said motor and said pump having a stationary valve body defining said intake and outlet, said stationary valve body being mounted on an upper portion of said housing, said motor being positioned beneath said housing and having its shaft extending up through the bottom of said housing and being connected to the rotatable casing of said pump, bearing means supporting said shaft intermediate said motor and pump, said bearing means being mounted on said housing, said fuel metering means comprising a first cylinder and piston, first check valve means withdrawing fuel from said chamber into said first cylinder, a second cylinder and piston, second check valve means returning fuel from said second cylinder into said chamber, a metered fuel output, third check valve means connecting said first cylinder to said output and also to said second cylinder, cam means driven by said motor for producing relative reciprocation of said cylinders and pistons, and adjustment means for adjusting the relative phase of movement of said cylinders and pistons, by virtue of all of which an adjustable metered fuel flow results from the differential pumping action of said cylinders and pistons.

2. A liquid-fuel burner accessory unit comprising a housing defining an airtight chamber, a liquid-ring pump having a suction intake for fuel and air and having an outlet feeding into said chamber for delivering compressed air and fuel into said chamber, said chamber formin an air-fuel se aration chamber, fuel level control means or controlling the uel level in said chamber, an output from said chamber for delivering compressed air therefrom, an electric motor connected to said liquid-ring pump for driving the pump, fuel metering means communicating with said chamber for delivering a metered fuel output therefrom, said fuel metering means including eccentric means driven by said motor, a first ring surrounding said eccentric means and having a first piston connected thereto, a second ring surrounding said eccentric means and having a second piston connected thereto, a first cylinder engaging said first piston and first swivel means supporting said first cylinder, first check valve means providing an intake to said first cylinder, 21 second cylinder engaging said second piston and second swivel means supporting said second cylinder, second check valve means providing an outlet from said second cylinder, a metered fuel output connection, third check valve means connecting said first cylinder to said output and also to said second cylinder, and adjustment means for adjusting the relative phase of movement of said pistons and cylinders for providing an adjustable metered output flow of fuel as a function of the differential pumping action of said cylinders and pistons. 

1. A liquid-fuel burner accessory unit comprising a housing defining an airtight chamber, a liquid-ring pump positioned within said chamber, said pump having a suction intake for fuel and air and having an outlet feeding into said chamber for delivering compressed air and fuel into said chamber, said chamber forming an air-fuel separation chamber, fuel level control means for controlling the fuel level in said chamber, an output from said chamber for delivering compressed air, fuel metering means communicating with said chamber for delivering a metered fuel output therefrom, an electric motor connected to said liquid-ring pump driving said pump, said pump having a rotating casing driven by said motor and said pump having a stationary valve body defining said intake and outlet, said stationary valve body being mounted on an upper portion of said housing, said motor being positioned beneath said housing and having its shaft extending up through the bottom of said housing and being connected to the rotatable casing of said pump, bearing means supporting said shaft intermediate said motor and pump, said bearing means being mounted on said housing, said fuel metering means comprising a first cylinder and piston, first check valve means withdrawing fuel from said chamber into said first cylinder, a second cylinder and piston, second check valve means returning fuel from said second cylinder into said chamber, a metered fuel output, third check valve means connecting said first cylinder to said output and also to said second cylinder, cam means driven by said motor for producing relative reciprocation of said cylinders and pistons, and adjustment means for adjusting the relative phase of movement of said cylinders and pistons, by virtue of all of which an adjustable metered fuel flow results from the differential pumping action of said cylinders and pistons.
 2. A liquid-fuel burner accessory unit comprising a housing defining an airtight chamber, a liquid-ring pump having a suction intake for fuel and air and having an outlet feeding into said chamber for delivering compressed air and fuel into said chamber, said chamber forming an air-fuel separation chamber, fuel level control means for controlling the fuel level in said chamber, an output from said chamber for delivering compressed air therefrom, an electric motor connected to said liquid-ring pump for driving the pump, fuel metering means communicating with said chamber for delivering a metered fuel output therefrom, said fuel metering means including eccentric means driven by said motor, a first ring surrounding said eccentric means and having a first piston connected thereto, a second ring surrounding said eccentric means and having a second piston connected thereto, a first cylinder engaging said first piston and first swivel means supporting said first cylinder, first check valve means providing an intake to said first cylinder, a second cylinder engaging said second piston and second swivel means supporting said second cylinder, second check valve means providing an outlet from sAid second cylinder, a metered fuel output connection, third check valve means connecting said first cylinder to said output and also to said second cylinder, and adjustment means for adjusting the relative phase of movement of said pistons and cylinders for providing an adjustable metered output flow of fuel as a function of the differential pumping action of said cylinders and pistons. 